1. Technical Field
The present invention relates generally to a steerable needle, and more particularly to an adjustable-bending stiffness steerable needle that can be easily and accurately steered to a target region to be treated through the passive or active control of bending stiffness during an intervention treatment procedure within a soft tissue.
Furthermore, the present invention relates generally to a steerable needle, and more particularly to a buckling-preventing steerable needle that can minimize damage to a soft tissue through the prevention of a buckling phenomenon, which may occur in a flexible needle, during an intervention treatment procedure within the soft tissue.
2. Description of the Related Art
In general, steerable needles are medical devices that are used to perform intervention treatment procedures, such as the tissue biopsies of the lesions of the breast, the abdomen, and various organs, the treatment of a lesion using high frequency, proximate treatment, medicine delivery, etc., within soft tissues by using elongated flexible needles. In particular, steerable needles have advantages in that they can expand a small acceptable area attributable to the limited mechanical characteristics of conventional stiff needles and also can improve the efficiency and accuracy of the approach of needles to targets.
As a related conventional art, U.S. Patent Application Publication No. US 2007/0016067 A1 discloses a technology for controlling a needle by using bending force provide to a bevel-shaped end while the needle having the bevel-shaped end is moving through a tissue, as shown in FIG. 1.
Various types of research are being conducted into a rectilinear steerable needle using external moment to reach a desired location, a steerable needle using the control of the relative locations of a plurality of sliding segments, etc. in addition to the above-described steerable needle using the bending phenomenon of a flexible needle including a tip having an obliquely cut end.
However, it is impossible to control the intrinsic bending stiffness of the conventional steerable needles, and thus the curvature of a path along which steering can be performed is small and it is difficult to perform accurate steering control due to the non-uniform characteristics of soft tissues.
Steerable needles use elongated flexible needles having low bending stiffness. In FIG. 1, a flexible needle 110 having an oblique end is shown. Referring to the upper view of FIG. 1, the flexible needle 110 is composed of a very thin, flexible wire or tube, and one end of the flexible needle 110 is composed of an oblique bevel tip. As shown in the lower view of FIG. 1, when the flexible needle 110 passes through a needle guide 118 and is then inserted into a soft tissue 112, the flexible needle 110 is steered and inserted along a planned path 114 by using the bending phenomenon of the needle that is generated by the interactive force between the oblique end and the soft tissue 112.
However, due to a small steering angle, it is difficult to insert the flexible needle 100 along a path having a large curvature. Furthermore, when the distance to which the needle is inserted is long or the needle encounters a hard region within a non-uniform soft tissue, an abrupt buckling phenomenon occurs within the tissue.
In other words, the tip of the needle is not moved any farther, and the insertion force used to insert the needle becomes a cause of the occurrence of the buckling phenomenon of the needle within the soft tissue. As shown in the lower view of FIG. 1, a buckling phenomenon in which the flexible needle 110 deviates from the planned path 114 occurs.
When the buckling phenomenon of the needle occurs, serious damage to the soft tissue, such as the cutting or tearing of the soft tissue, may be caused. When a flexible needle having higher bending stiffness is used due to concern about such a buckling phenomenon, the curvature of a path along which steering can be performed becomes low, and thus a limitation arises in that applicable treatment procedures are limited due to a small acceptable area.
Therefore, there are needs for a steerable needle capable of controlling bending stiffness and accurately controlling steering and a steerable needle capable of preventing a buckling phenomenon, which can overcome the above-described problems.